Delayed duplicate I-picture for video coding

Abstract

A method is provided that includes receiving pictures of a video sequence in a video encoder, and encoding the pictures to generate a compressed video bit stream that is transmitted to a video decoder in real-time, wherein encoding the pictures includes selecting a picture to be encoded as a delayed duplicate intra-predicted picture (DDI), wherein the picture would otherwise be encoded as an inter-predicted picture (P-picture), encoding the picture as an intra-predicted picture (I-picture) to generate the DDI, wherein the I-picture is reconstructed and stored for use as a reference picture for a decoder refresh picture, transmitting the DDI to the video decoder in non-real time, selecting a subsequent picture to be encoded as the decoder refresh picture, and encoding the subsequent picture in the compressed bit stream as the decoder refresh picture, wherein the subsequent P-picture is encoded as a P-picture predicted using the reference picture.

What is claimed is: 
     
       1. A method comprising:
 receiving pictures of a video sequence in a video encoder, the pictures including a first picture followed by a second picture followed by a third picture; and 
 encoding the pictures in the video encoder to generate a compressed video bit stream, wherein encoding the pictures includes:
 encoding the first picture as an intra-predicted picture (I-picture); 
 reconstructing the I-picture to generate a first reference picture; 
 encoding the second picture as a P-picture; and 
 generating a decoder refresh picture at least in part by encoding the third picture as a P-picture that is predicted using the first reference picture, 
 wherein the decoder refresh picture indicates that all pictures after the decoder refresh picture will not refer to any reference pictures preceding the decoder refresh picture except for the first picture. 
 
 
     
     
       2. The method of  claim 1 , wherein the third picture is followed by one or more additional pictures, the method further comprising:
 encoding the additional pictures as additional P-pictures such that the additional P-pictures do not refer to any reference pictures preceding the decoder refresh picture except for the first picture. 
 
     
     
       3. The method of  claim 1 , wherein the pictures of the video sequence include one or more pictures between the second and third pictures. 
     
     
       4. The method of  claim 1 , wherein encoding the first picture includes encoding the first picture into a first bit stream, wherein encoding the second picture includes encoding the second picture into the compressed video bit stream, and wherein encoding the third picture includes encoding the third picture into the compressed video bit stream, the method further comprising:
 transmitting the first bit stream according to a first network protocol; and 
 transmitting the compressed video bit stream according to a second network protocol. 
 
     
     
       5. The method of  claim 4 , wherein the first network protocol and the second network protocol are a same network protocol. 
     
     
       6. The method of  claim 1 , wherein encoding the first picture includes encoding the first picture into a first bit stream, wherein encoding the second picture includes encoding the second pictured into the compressed video bit stream, and wherein encoding the third picture includes encoding the third picture into the compressed video bit stream, the method further comprising:
 transmitting the first bit stream in non-real time; and 
 transmitting the compressed video bit stream in real time. 
 
     
     
       7. The method of  claim 1 , wherein the video encoder is included in a video conferencing system. 
     
     
       8. The method of  claim 1 , wherein encoding the first picture includes encoding the first picture into a first bit stream as the I-picture, wherein encoding the second picture includes encoding the second picture into the compressed video bit stream, and wherein encoding the third picture includes encoding the third picture into the compressed video bit stream, the method further comprising:
 encoding the first picture into the compressed video bit stream as a P-picture. 
 
     
     
       9. The method of  claim 8 , further comprising:
 transmitting the first bit stream according to a first network protocol; and 
 transmitting the compressed video bit stream according to a second network protocol. 
 
     
     
       10. The method of  claim 9 , wherein the first network protocol and the second network protocol are a same network protocol. 
     
     
       11. The method of  claim 8 , further comprising:
 transmitting the first bit stream in non-real time; and 
 transmitting the compressed video bit stream in real time. 
 
     
     
       12. A video encoder device comprising one or more processors configured to:
 receive pictures of a video sequence, the pictures including a first picture followed by a second picture followed by a third picture; 
 encode the first picture as an intra-predicted picture (I-picture); 
 reconstruct the I-picture to generate a first reference picture; 
 encode the second picture as a P-picture; and 
 generate a decoder refresh picture at least in part by encoding the third picture as a P-picture that is predicted using the first reference picture, 
 wherein the decoder refresh picture indicates that all pictures after the decoder refresh picture will not refer to any reference pictures preceding the decoder refresh picture except for the first picture. 
 
     
     
       13. The device of  claim 12 , wherein the third picture is followed by one or more additional pictures, the one or more processors further configured to:
 encode the additional pictures as additional P-pictures such that the additional P-pictures do not refer to any reference pictures preceding the decoder refresh picture except for the first picture. 
 
     
     
       14. The device of  claim 12 , wherein the pictures of the video sequence include one or more pictures between the second and third pictures. 
     
     
       15. The device of  claim 12 , wherein the one or more processors are further configured to:
 encode the first picture into a first bit stream; 
 encode the second and third pictures into a compressed video bit stream; 
 transmit the first bit stream according to a first network protocol; and 
 transmit the compressed video bit stream according to a second network protocol. 
 
     
     
       16. The device of  claim 15 , wherein the first network protocol and the second network protocol are a same network protocol. 
     
     
       17. The device of  claim 12 , wherein the one or more processors are further configured to:
 encode the first picture into a first bit stream; 
 encode the second and third pictures into a compressed video bit stream; 
 transmit the first bit stream in non-real time; and 
 transmit the compressed video bit stream in real time. 
 
     
     
       18. The device of  claim 12 , wherein the video encoder device is included in a video conferencing system. 
     
     
       19. The device of  claim 12 , wherein the one or more processors are further configured to:
 encode the first picture into a compressed video bit stream as a P-picture. 
 
     
     
       20. The device of  claim 19 , wherein the one or more processors are further configured to:
 encode the first picture into a first bit stream as the I-picture; 
 encode the second and third pictures into the compressed video bit stream; 
 transmit the first bit stream according to a first network protocol; and 
 transmit the compressed video bit stream according to a second network protocol. 
 
     
     
       21. The device of  claim 20 , wherein the first network protocol and the second network protocol are a same network protocol. 
     
     
       22. The device of  claim 19 , wherein the one or more processors are further configured to:
 encode the first picture into a first bit stream as the I-picture; 
 encode the second and third pictures into the compressed video bit stream; 
 transmit the first bit stream in non-real time; and 
 transmit the compressed video bit stream in real time. 
 
     
     
       23. A non-transitory computer-readable medium comprising instructions that, when executed by one or more processors, cause the one or more processors to:
 receive pictures of a video sequence, the pictures including a first picture followed by a second picture followed by a third picture; 
 encode the first picture as an intra-predicted picture (I-picture); 
 reconstruct the I-picture to generate a first reference picture; 
 encode the second picture as a P-picture; and 
 generate a decoder refresh picture at least in part by encoding the third picture as a P-picture that is predicted using the first reference picture, 
 wherein the decoder refresh picture indicates that all pictures after the decoder refresh picture will not refer to any reference pictures preceding the decoder refresh picture except for the first picture.